When President Xi Jinping arrived at the Mar-a-Lago resort in Florida three months ago for his first personal meeting with US counterpart Donald Trump, much of the world’s attention was on whether the two alpha males could get along to steady the fraught bilateral relations.

Now as the pair head into a meeting at the G20 summit that opens in Hamburg, Germany on Friday, the stakes could be even higher amid unexpected escalating tensions over North Korea’s nuclear threats.

Pyongyang’s latest provocation, which saw the launch of its first intercontinental ballistic missile threatening the US mainland on Tuesday, has not only hijacked the agenda of the planned second summit between the two, but also could push Beijing and Washington towards a showdown, according to observers.

Tensions between the two powers have flared over the past week as Beijing and Washington have exchanged barbs over a raft of contentious issues, including Taiwan, the South China Sea dispute, trade rifts and the treatment of terminally ill political dissident and Nobel peace laureate Liu Xiaobo.

The two leaders’ failure to patch things up during a telephone call on Monday over their divergent interests on major geopolitical challenges basically set the stage for their sit-down meeting planned on the sidelines of the two-day summit, Chinese experts said.

Xi’s rare admission that bilateral ties have been hampered by negative factors showed Beijing’s displeasure with Trump’s China policy, said Shi Yinhong, a US expert from Beijing’s Renmin University.

“We are seeing the return of US-China relations to normalcy and the short-lived honeymoon [since their first summit] has come to an end,” he said.

Shi said relations between the world’s top two economies potentially became volatile and stood to suffer further blows when Trump deliberately staked US-China ties on one single issue: North Korea.

“There is no imminent solution to North Korea’s nuclear threats and I don’t think Trump will ever be satisfied with whatever Xi may have to offer,” he said.

Both Shi and Zhang Liangui, a Korean affairs expert from the Central Party School in Beijing, said it was unrealistic to expect Xi and Trump to break their deadlock on North Korea at the meeting or any time soon.

“It is a pity that both leaders appear to have failed to realise that they’ve been played off against each other by Kim Jong-un, who has deftly used his nuclear weapons programme to advance his personal ambition while driving a wedge between the two powers,” Zhang said.

Other world leaders, such as Japanese Prime Minister Shinzo Abe and South Korean President Moon Jae-in, are also expected to join Trump’s effort in their separate meetings with Xi to ratchet up the pressure on China for tougher economic and trade actions on North Korea, such as banning crude oil exports.

Although China has begun to see Pyongyang as a liability amid growing threats of its reckless nuclear brinkmanship, top leaders in Beijing still view North Korea as a buffer and are hesitant to impose tougher sanctions on the reclusive state for fear of the collapse of the Kim regime and chaotic repercussions in the peninsula.

Steve Tsang, director of the SOAS China Institute in London, said Xi may have little to offer on North Korea.

“Xi will tell Trump and others again how difficult Kim is and how few levers he has over Kim, so he would need more time and understanding to get Kim to behave better. I doubt that this would work very well,” Tsang said.

Shi Yinhong also said Beijing was likely to continue with its stalling tactics on North Korea to counter mounting international pressure.

“Even if China agrees to tighten the screw on North Korea, such as cutting oil supplies and suspending bilateral trade, there is no guarantee it would bring Kim in line. If China exhausts all of its options on North Korea, it will put Beijing in a more embarrassing and vulnerable position,” he said.

Hwang Jaeho, an expert from the Hankuk University of Foreign Studies in Seoul, noted US Secretary of State Rex Tillerson said North Korea’s launch of the intercontinental ballistic missile represented a new escalation of the threat and vowed to take stronger measures to hold Pyongyang accountable.

On Monday, China’s ambassador to the UN, Liu Jieyi, who holds the security council presidency this month, warned that tensions “sooner or later” could get out of control, leading to “disastrous” consequences, and called for the resumption of multi-party talks on denuclearisation.

“But I am not sure how much concession China will make because, for Beijing and Xi personally, maintaining stability on the Korean peninsula is apparently its primary concern ahead of the sweeping reshuffle at the party congress later this year,” Hwang said.

The G20 gathering of world leaders of industrialised nations and emerging economies comes just days after Washington made a flurry of moves targeting China, including approving the first batch of arms sales to Taiwan under Trump totalling US$1.4 billion and a bill approved by the US Senate Armed Services Committeeto enhance military exchanges with the self-ruling island.

China-US relations were further strained by the passage of a US naval vessel less than 12 nautical miles from a Chinese-claimed island in the Paracel Islands on Sunday, which Beijing denounced as “a serious political and military provocation”.

Experts warned that since the first summit between Xi and Trump, which was widely hailed as establishing an unusual rapport between the two leaders, both sides have harboured misconceptions about each other.

“I think Trump had a very misguided idea about what he could achieve on the basis of one meeting with Xi. China’s ‘failure’, whether it is due to half-heartedness or not, is a demonstration that Trump’s simplistic thinking was just that,” said Jonathan Sullivan, director of the China Policy Institute at the University of Nottingham.

The abrupt end of the temporary “bromance” between Trump and Xi seems likely to result in Trump going to the other extreme in his assessment of his relationship with Xi by exacerbating frictions with China, Sullivan warned.

Beijing also appeared to have become overconfident in its expectations on US policy and Xi’s ability to handle Trump since their first meeting, said Huang Jing of the National University of Singapore.

“It is rather naive to put all the eggs in one basket while forgetting the fact that Trump is a weak, embattled leader who needs to be managed by the Republican establishment, who are opposed to Trump’s softer approach towards China,” he said.

Lester Ross, managing partner at US law firm Wilmer Hale, also warned that Chinese officials may have failed to recognise that the “direction of US diplomacy policy may change” drastically.

“Because the [Trump] administration was new to office and President Trump did not have a fully formed view of the world, it is quite possible that early signals which it gave would not in fact be sustained.

“There may be a sense of satisfaction and success in China [in dealing with Trump], but we may see some tough times ahead unless China can make changes,” said Ross, who also sits on the board of governors of the American Chamber of Commerce in China.

Trade rifts, which were set aside along with other thorny bilateral differences as a quid pro quo in exchange for Beijing’s concession on North Korea, look set to intensify.

“China may have thought it could offer to make minor [concessions] in their own interest with little cost, which would be sufficient to satisfy the Trump administration. I don’t think that is necessarily the case,” Ross said. “In fact, the Trump administration will be tougher on trade in particular, possibly on investment and, separately, will ask more on North Korea than China may be able to deliver,” he said.

“[The] bilateral trade relationship will be on eggshells until Trump knows what he plans to do with China,” said James Zimmerman, former chairman with the American Chamber of Commerce in China. “It won’t lead to a trade war but lead to more tension.”

Both sides reached a 10-point trade deal in April as an initial result of trade and economic talks between Beijing and Washington after Xi and Trump met in Florida in April. But the deal was criticised as lacking in depth and offering little substance.

“It was not an incredible breakthrough. However, timing is not good for China as it is preoccupied with the 19th Communist Party Congress this fall,” Zimmerman said. “China may come on the radar screen and in much the way it did during the presidential election. We must be careful not to allow the tension to override good things,” he added.

Observers said both leaders need to take stock of the bilateral ties and try to work out ways to expand their cooperation on other vital interests, pending the settlement of the North Korea crisis.

“For too long, North Korea has been the only glue that held the US and China together. But this glue has always been too brittle to carry the relations by itself,” said Gal Luft, co-director of the Washington-based Institute for the Analysis of Global Security,a US think tank.

“Paradoxically, by launching a missile prior to the Xi-Trump meeting at the G20 summit, Kim did an important service to US-China relations because his action will force the two leaders to seek ways to broaden the relations and pursue new common interests. It is important not to let Kim feel that his shenanigans can cause a rift between the US and China as this will only embolden him and bolster his illusion of grandeur,” he said.

Luft and other experts also warned that China must come up with plans to avoid escalating tensions as Washington might revive its consideration of a pre-emptive military strike against North Korea.

Trump’s national security adviser H.R. McMaster said last week that the Trump administration is considering a range of options amid escalating tensions in the Korean Peninsula, “including a military option, which nobody wants to take”.

Xi should assume leadership over the diplomatic option on North Korea as it is the only possible course of action short of a devastating military solution that Washington may consider taking, Luft suggested.

“Xi can coalesce Russia, South Korea and other members of the UN Security Council to create a unified block favouring diplomacy. Such a block will counter any US-led international architecture in support of a military solution,” he said.